A flail is a weapon consisting of a striking head attached to a handle by a flexible rope, strap, or chain. The chief tactical virtue of the flail was its capacity to strike around a defender's shield or parry. Its chief liability was a lack of precision and the difficulty of using it in close combat, or closely-ranked formations.
Spiked versions of long-handled peasant flails. From Paulus Hector Mair's combat manual Arte De Athletica
16th century peasant rebels
Modern representation of a one-handed flail
Detail from Battle between Heraclius and Chosroes, painted by Piero della Francesca circa 1452, showing a short flail with three spherical striking ends
A morning star is any of several medieval club-like weapons consisting of a shaft with an attached ball adorned with one or more spikes, each used, to varying degrees, a combination of blunt-force and puncture attack to kill or wound the enemy.
A morning star (middle) shown among other club designs
Morning star (left), next to a ball-and-chain flail (right).